Rapid Fiver: Is 10k steps a myth? And four other things to know!
Editor’s Note: Hi there! Samarth Bansal here, your Editor. Today, I am writing our curated edition where we share our favourite health content from outside the TBT universe. Five things.?
One: ‘10k Steps a Day’ is a Marketing Myth?
Most of you’ve heard it and some of you swear by it: the idea that we should all aim for 10,000 steps per day as a fitness goal. What many of you might know—I didn’t until recently—is that this number is largely a marketing construct and is not based on solid scientific evidence.
Here’s the origin story : In the 1960s, the Japanese company ‘Yamasa Clock’ created a pedometer (i.e. step-counter) to capitalise on the fitness craze emerging in the run up to the 1964 Tokyo Olympics. Those guys came up with the 10,000 steps a day recommendation as the target number of steps people should take to promote their device.?
How did they arrive at this magic number? Hold your breath: Because the Japanese character for 10,000 looks like a person walking. See for yourself.?
I find this a bit amusing. I have had my phase of peak obsession with hitting the 10k number—9k would make me feel like a douchebag—only to know that some person, sixty years ago, just got a visual inspiration from a Japanese character? Lol.?
No wonder they named the device ‘Manpo-kei’—which means ‘10,000 steps metre’ in Japanese. Clearly, the messaging worked: the number persists in popular consciousness till date.?
What to make of it? Three thoughts from me:?
1) It’s a reminder that numerical targets in fitness are promoted despite limited scientific backing. It helps—when you have mental bandwidth and interest—to question what’s considered normal. New research claims that? 7,500 steps a day might be just as useful.?
2) Yet, I do think this number actually helped me during my fat loss phase to serve as a useful reminder to move more. And helped me add consistent movement through the day. As in trying to hit this arbitrary number revealed my sedentary habits. So I started looking for opportunities to walk—many of which have stuck till date: always taking stairs instead of elevators; parking a little away to walk a bit; walking during calls when machines are not needed. So I don’t feel too pissed off with it either.?
Two: A Fresh History of Lactose Intolerance (The New Yorker)
This story in The New Yorker offers a fascinating review of ‘Spoiled’ by Anne Mendelson, a book that explores the historical and cultural context of milk consumption. (It’s paywalled—so I have uploaded a PDF here .)
It traces how this myth originated: Milk drinking started in prehistoric Western Asia and Northern Europe, where a genetic mutation allowed some adults to digest lactose, meaning people in these geographies could now digest fresh milk.?
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However, Mendelson writes, for most outside these regions, lactose intolerance is the norm—tolerance is the exception.?
And yet, despite this evidence of widespread lactose intolerance—especially among non-European populations—milk has been marketed as a nutritional necessity, demonstrating how societal and commercial forces shape health beliefs. She traces how, as colonial powers like Britain expanded, they spread the faulty belief that all people could digest fresh milk.
To be sure, the article is not making a blanket case against drinking milk or dairy (that’s a separate discussion). It cites examples, like in India, where fermented milk—rather than fresh milk—has an important place in the cuisine, like dahi, paneer and chhena.?
In short, Mendelson argues the myth that all people require fresh milk ignores science and the reality of lactose intolerance. She advocates re-examining this myth and considering alternative milks.
For me, there is another lesson here: Just like the previous example of 10,000 steps being a marketing construct, normalisation of dietary beliefs can emerge from limited evidence that is over-generalized. In this case, a genetic trait in some populations was wrongly assumed to apply to all.?
Societal attitudes and early traditions acquire an authoritative status as “normal” over time, even if based on limited knowledge. And in that sense, this piece nudges us to be more mindful of nutritional orthodoxies.?
Three:? How One Disease Changed What We Know About Medicine— Twice
Too much of something good can be bad. Doctors learned this when they tried to prevent rickets in kids by adding lots of vitamin D to food. (Rickets is a bone disease caused by vitamin D deficiency.)
However, they then discovered the problems caused by excess vitamin D, like high calcium levels in the blood, leading to kidney problems. It took many years to understand why.
This video talks about two studies that get into the reasons—and evolving understanding—of why ?more-than-needed levels of vitamin D affect some kids but not everyone.?
1) In a 2011 study, researchers found that certain kids have differences in their DNA that make it hard to process high doses of vitamin D. These DNA differences are a mutation in a gene called CYP24A1.
This gene helps the body manage vitamin D by breaking down any excess. However, the mutation can stop this process, leading to too much vitamin D in the body. People with this mutation can’t properly control their vitamin D levels, which can result in high calcium levels in their blood, kidney problems, and other health issues.
2) Then, in a 2023 study, researchers focused on those who still had problems with excess vitamin D but didn’t have the mutation. This one is a bit technical, but here is the gist.?
There are protein-coding parts of DNA and non-coding parts. The protein-coding parts contain instructions to make proteins, which do most of the work in our cells. That’s why scientists used to think only those parts mattered. And the non-coding parts were assumed to be “junk” DNA without important functions.?
But the 2023 study revealed that even these non-coding parts—which make up 98% of our DNA—can play an important role. It can cause disease by affecting the body’s complex chemistry.
The lesson here? When we try to “fix” dietary deficiencies with fortified foods or supplements, there can be unintended consequences. Our bodies are complex systems—and each body responds uniquely. New forms of foods or high doses of nutrients may have different effects compared to getting them naturally through diet. (It’s unlikely that vitamin D from sunlight would lead to an excess.)
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